Wafer processing

ABSTRACT

Methods, devices, and systems for wafer processing are described herein. One method of wafer processing includes modifying a peripheral edge of a wafer to create a number of edge surfaces substantially perpendicular to a number of dicing paths and dicing the wafer along the number of dicing paths. In one or more embodiments, the method includes modifying the peripheral edge of the wafer with a first tool and dicing the wafer with a second tool different from the first tool.

PRIORITY APPLICATION INFORMATION

This application is divisional of U.S. application Ser. No. 11/966,705,filed Dec. 28, 2007, the specifications of which are incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates generally to wafer processing and, moreparticularly, to processing of wafers used in electronic semiconductorsystems and devices.

BACKGROUND

Integrated circuits (ICs) form the basis for many electronic systems.Essentially, an integrated circuit (IC) includes a vast number oftransistors and other circuit elements that are formed on a singlesemiconductor wafer or semiconductor chip and are interconnected toimplement a desired function. Increasing complexity of these ICs leadsto an increasing number of linked transistors and other circuitelements.

An individual integrated circuit or chip is usually formed from a largerstructure known as a semiconductor wafer, which can be comprised ofvarious materials such as silicon, gallium arsenide, indium phosphide,ceramic, copper, glass, glass-ceramic, lithium niobate, quartz,sapphire, silicon on insulator, and/or silicon on sapphire glass, amongvarious other materials. Such wafers often have round peripheries andcan have a plurality of integrated circuits arranged in rows and columnswith the periphery of each integrated circuit being rectangular. Thewafer can be sawn or “diced” into rectangularly shaped discreteintegrated circuits along two mutually perpendicular sets of parallellines, e.g., streets, lying between each of the rows and columnsthereof. Hence, the separated or singulated integrated circuits arecommonly referred to as dice.

An example, a wafer sawing operation can include attaching the wafer toa wafer saw carrier, mechanically, adhesively or otherwise, as known inthe art, and mounting the wafer saw carrier on the table of the wafersaw. A blade of the wafer saw is passed through the surface of the waferby moving either the blade relative to the wafer or the table of the sawand the wafer relative to a stationary blade, or a combination of both.In various cases, to dice the wafer, the blade cuts precisely along eachstreet, returning back over (but not in contact with) the wafer whilethe wafer is laterally indexed to the next cutting location. Once allcuts associated with mutually parallel streets having one orientationare complete, the blade can be rotated 90 degrees relative to the waferor the wafer can be rotated 90 degrees, and cuts can be made throughstreets in a direction perpendicular to the initial direction of cut.

Various dicing blades are available commercially. By way of example, asintered diamond blade includes diamond particles which are fused into asoft metal such as brass or copper, or incorporated by means of apowdered metallurgical process; a plated diamond blade includes diamondparticles which are held in a nickel bond produced by an electroplatingprocess; and a resinoid diamond blade is one in which diamond particlesare typically held in a resin bond to create a homogeneous matrix, amongvarious other dicing blades.

The type of dicing blade used to dice a wafer can depend on variousfactors such as the type of wafer. For instance, the type of dicingblade used can depend on whether the wafer is comprised of silicon,glass, ceramic, sapphire, and/or a combination thereof. In some cases,the wafer can be a number of wafers bonded together forming a waferstack. In such cases, each wafer of the stack can be comprised of adifferent material or a combination of different materials.

In dicing operations, the sharpness of the tool blade can affect theeffectiveness of the cutting and/or the yield of a wafer dicing process.The blade sharpness can be affected by various factors including bladespeed, torque, depth of cut, and feed rate, among others. Dull dicingblades can slow the wafer dicing process, which can cause problems suchas reduced throughput as blades are replaced and/or sharpened. The highcost of these wafers, together with the value of the circuits fabricatedon them, makes it difficult to accept anything less than high yield atthe die-separation phase.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a top view of a wafer to be diced in accordance witha previous wafer processing approach.

FIG. 1B illustrates a perspective view of the wafer stack shown in FIG.1A.

FIG. 1C illustrates an exploded cross-sectional view of the wafer stackshown in FIG. 1B taken along line 1C-1C.

FIG. 1D illustrates a cross-sectional view of a number of unsingulateddice corresponding to the wafer stack shown in FIG. 1B.

FIG. 1E illustrates a cross-sectional view of the dice shown in FIG. 1Dafter being singulated.

FIG. 2 illustrates a top view of a wafer to be diced in accordance withembodiments of the present disclosure.

FIG. 3A illustrates a top view of the wafer shown in FIG. 2 subsequentlyto being modified in accordance with an embodiment of the presentdisclosure.

FIG. 3B illustrates a perspective view of a wafer stack subsequently tobeing modified in accordance with an embodiment of the presentdisclosure.

FIG. 4A illustrates a wafer processing system according to an embodimentof the present disclosure.

FIG. 4B illustrates a wafer processing system according to an embodimentof the present disclosure.

FIG. 5 illustrates a lens stack device in accordance with an embodimentof the present disclosure.

FIG. 6 illustrates a block diagram of an electronic system having atleast one lens stack device formed in accordance with an embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Methods, devices, and systems for wafer processing are described herein.One method of wafer processing includes modifying a peripheral edge of awafer to create a number of edge surfaces substantially perpendicular toa number of dicing paths and dicing the wafer along the number of dicingpaths. In one or more embodiments, the method includes modifying theperipheral edge of the wafer using a first processing method and/or tooland dicing the wafer using a second processing method and/or tooldifferent from the first.

In the following detailed description of the present disclosure,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration how one or more embodimentsof the disclosure may be practiced. These embodiments are described insufficient detail to enable those of ordinary skill in the art topractice the embodiments of this disclosure, and it is to be understoodthat other embodiments may be utilized and that process, electrical,and/or structural changes may be made without departing from the scopeof the present disclosure.

As used in this disclosure, the terms “wafer” and “substrate” are usedinterchangeably and are to be understood as including, but not limitedto, silicon-on-insulator (SOI) or silicon-on-sapphire (SOS) technology,doped and undoped semiconductors, epitaxial layers of silicon supportedby a base semiconductor foundation, and other semiconductor structures.Furthermore, when reference is made to a “wafer” or “substrate” in thefollowing description, previous process steps may have been utilized toform regions or junctions in the base semiconductor structure orfoundation.

FIGS. 1A-1E illustrate various views of a wafer 101 to be diced inaccordance with a previous wafer processing approach. In the exampleillustrated in FIGS. 1A-1E, the wafer 101 is a wafer stack 101, e.g., anumber of wafers bonded together as illustrated in FIG. 1B. Embodimentsof the present disclosure are not limited to wafer stacks or to aparticular number and/or type of wafer.

FIG. 1A illustrates a top view of a wafer 101 to be diced in accordancewith a previous wafer processing approach. As illustrated in FIG. 1A,the wafer 101 has a round peripheral edge 109. The wafer 101 includes anumber of dice 115 having streets 105 located there between. As usedherein, streets 105 may be referred to as dicing paths 105, e.g., pathsalong which a tool may cut in order to singulate the dice 115. As one ofordinary skill in the art will appreciate, various processing methodsand/or tools can be used to dice a wafer. Examples of tools include, butare not limited to, rotating saw blades, laser cutters, and water jetcutters.

In many cases, and as shown in FIG. 1A, the dice 115 are formed on thewafer such that the dicing paths 105 are mutually parallel to each otherin a first and second direction. For instance, the paths 105 in a firstdirection, e.g., the horizontal direction relative to a chosen referencepoint on a given wafer, are parallel to each other and the paths 105 ina second direction, e.g., the vertical direction, are parallel to eachother. In such cases, and as shown in FIG. 1A, the horizontal andvertical dicing paths 105 can be perpendicular to each other.

In various previous wafer processing approaches, one or more rotatingsaw blades are used to singulate the dice 115 by cutting along thestreets 105. In such approaches, the saw blade enters the peripheraledge 109 of the wafer 101 at a blade entry point, e.g., 107, such thatthe blade is aligned with a particular street 105. As such, the sawblade enters the peripheral edge 109 at different angles depending onthe shape of the peripheral edge 109 of the wafer 101 and depending onthe location of the particular street 105 and associated blade entrypoint 107. For instance, in the example shown in FIG. 1A, the peripheraledge 109 of the wafer 101 is round, e.g., wafer 101 is a round wafer,such that the angle at which the blade enters becomes less and lessperpendicular to the edge 109 as the streets 105 move further from themiddle of the wafer 101. That is, in this example, the saw blade entersthe wafer nearly perpendicularly to the peripheral edge for streets 105located near the middle of wafer 101 and the blade entry angle becomesless and less perpendicular to the edge 109 for streets 105 locatedfurther from the middle of the wafer 101.

Blade entry angles which are not perpendicular to the peripheral edge,e.g., 109, of a wafer can cause the dicing blade to meaningfully deflectand/or wobble as it makes contact with the peripheral edge at the bladeentry point, e.g., 107. Such blade deflection and/or wobbling can causea variety of issues such as reducing the quality or accuracy of the cutand/or damage to the dicing blade, among other issues. The amount ofblade deflection can be affected by various factors such as the type ofwafer and/or the thickness of the wafer being diced, among otherfactors. For instance, the problems associated with blade entry angleswhich are not perpendicular to the peripheral edge can become morepronounced for thicker wafers and/or wafers comprised of hardermaterials. As one example, the deflection and/or wobbling associatedwith non-perpendicular blade entry angles may be less for a siliconwafer than for a wafer comprised of a material such as glass or quartz,for example. Also, in some cases, and as described further in connectionwith FIG. 1B, a stack of wafers that are bonded together may be dicedsimultaneously. In such cases, the deflection and/or wobbling associatedwith a wafer stack can be greater than that associated with a singlewafer having a smaller thickness.

FIG. 1B illustrates a perspective view of the wafer stack 101 shown inFIG. 1A. As described above, the wafer stack 101 includes a number ofdice 115 to be singulated via sawing along streets 105 located betweenthe dice 115. As explained above, to singulate the dice 115, a sawblade, e.g., 125, makes contact with the peripheral edge 109 of thestack 101 at a number of blade entry points 107. In the example shown inFIG. 1B and as described above, the peripheral edge 109 is round suchthat the angle at which the blade 125 enters the wafer is notsubstantially perpendicular to the peripheral edge 109 at entry points107.

In the example illustrated in FIG. 1B, the wafer stack 101 includes anumber of wafers bonded together, e.g., wafers 102, 104, and 106. Eachof the wafers 102, 104, and 106 can be comprised of one or morematerials and each layer can have a different thickness. An example ofthe type of wafers 102, 104, and 106 in wafer stack 101 is shown in FIG.1C.

FIG. 1C illustrates an exploded cross-sectional view of the wafer stackshown 101 in FIG. 1B taken along line 1C-1C. In this example, the waferstack 101 is a lens stack 101 that includes a first lens wafer 102, asecond lens wafer 104, and a spacer wafer 106.

In the example illustrated in FIG. 1C, the wafer 102 includes a glasswafer core 111, a first optical polymer layer 112-1, and a secondoptical polymer 112-2. As illustrated in FIG. 1C, the wafer 102 includesa number of concave lenses 116 formed on layer 112-2 and a correspondingnumber of convex lenses 114 formed on layer 112-1. The wafer 104includes glass wafer core 121, a first optical polymer layer 122-1, anda second optical polymer 122-2. As illustrated in FIG. 1C, the wafer 104includes a number of concave lenses 126 formed on layer 122-1 and acorresponding number of convex lenses 124 formed on layer 122-2. In theexample illustrated in FIG. 1C, the spacer wafer 106 is formed of aglass material 131 and has a number of apertures 133 therethrough.

The wafers 102, 104, and 106 can be aligned and bonded together via anepoxy or other bonding agent to form a lens stack 101. FIG. 1Dillustrates a cross-sectional view of a number of unsingulated dicecorresponding to the wafer stack 101 shown in FIG. 1B. The aligned stackof wafers 102, 104, and 106 can be singulated into individual dies bybeing diced along streets 105.

FIG. 1E illustrates a cross-sectional view of the dice shown in FIG. 1Dafter being singulated. That is, FIG. 1E illustrates a number ofsingulated dice 115-1, 115-2, 115-3, and 115-4. In this example, each ofthe singulated dice can be an individual lens stack, or lens assembly115-1, 115-2, 115-3, and 115-4. Although only four dice, e.g., lensassemblies 115-1, 115-2, 115-3, and 115-4, are shown in this example, awafer stack such as stack 101 can include 2,000-3,000 or more dice.Embodiments are not limited to wafer stacks having a particular numberof dice formed thereon, e.g., a wafer and/or wafer stack can includemore or less than 2,000-3,000 dice. As described further in connectionwith FIGS. 5 and 6, the lens assemblies 115-1, 115-2, 115-3, and 115-4can be bonded to other dice, e.g., dice containing image sensors orother electrical components, to form lens devices that can be used inelectronic devices and/or systems such as cellular telephones, digitalcameras, and/or telecommunication systems, among others.

In some embodiments, the wafer stack 101 can be coupled to, e.g.,bonded, to one or more other wafers or wafer stacks prior to beingsingulated into individual dice. For instance, the lens stack 101 can bealigned with and bonded to a wafer having a number of image sensor diceprior to being singulated. In such embodiments, the singulated lensstack devices, e.g., the individual stacks of a lens assembly die and animage sensor die, can be used in various optical devices and systems.

FIG. 2 illustrates a top view of a wafer 201 to be diced in accordancewith embodiments of the present disclosure. The wafer 201 includes anumber of dice 215 to be singulated. As described above, in one or moreembodiments, the wafer 201 can be a stack of wafers bonded together.

In one or more embodiments, the wafer 201 includes a peripheral edge209-1. In the example shown in FIG. 2, the peripheral edge 209-1 isinitially round, but embodiments of the present disclosure are notlimited to round wafers, e.g., wafers having a circular periphery. Forinstance, as one of ordinary skill in the art will appreciate, in someembodiments, the wafer 201 may initially have a flat edge that can beused for wafer stack alignment, for example.

In one or more embodiments, the initial peripheral edge, e.g., 209-1, ofthe wafer is modified, e.g., changed, to create a number of edgesurfaces substantially perpendicular to a number of dicing paths. In oneor more embodiments, the number of edge surfaces that are created is atleast five. As used herein, an initial peripheral edge of a wafer refersto the peripheral edge of a wafer prior to being changed to create thenumber of edge surfaces which are substantially perpendicular to thenumber of dicing paths. For instance, in the example shown in FIG. 2,the wafer 201 initially has a peripheral edge 209-1. In one or moreembodiments, the initial peripheral edge 209-1 is modified such that anumber of edge surfaces 209-2 and 209-3 are created. That is, a numberof edge portions 255 of the wafer 201 can be removed to create one ormore edge surfaces 209-2 and 209-3 which are substantially perpendicularto the dicing paths 205. As illustrated in FIG. 2, the modified edgesurfaces 209-2 and 209-3 can be perpendicular to each other. In one ormore embodiments, the number of removed portions 255 is at least four.In some embodiments, the modified edge surface 209-2 associated witheach removed portion 255 is perpendicular to at least one horizontaldicing path and the modified edge surface 209-3 associated with eachremoved portion 255 is perpendicular to at least one vertical dicingpath.

In the example shown in FIG. 2, the edge surfaces 209-2 are formed suchthat they are substantially perpendicular to horizontal dicing paths205, while the edge surfaces 209-3 are formed such that they aresubstantially perpendicular to vertical dicing paths 205. Although onlyhorizontal dicing paths 205 are shown between the dice 215, as describedabove in connection with FIG. 1A, vertical dicing paths which areperpendicular to the horizontal dicing paths also exist between theunsingulated dice 215.

In one or more embodiments, the edge surfaces 209-2 and 209-3, which arecreated by changing the initial peripheral edge 209-1 of the wafer 201,are blade entry surfaces 209-2 and 209-3. In such embodiments, one ormore of edge surfaces 209-2 and 209-3 are diced along dicing paths 205via a rotating saw blade. Since the blade entry surfaces 209-2 and 209-3are perpendicular to the dicing paths 205, the blade, e.g., 225,contacts an edge surface, e.g., 209-2, perpendicular to the edgesurface. For instance, for dicing along horizontal dicing paths, the sawblade 225 has a perpendicular entry angle with respect to the bladeentry surface 209-2.

Changing the initial peripheral edge 209-1 of wafer 201 can occur via anumber of suitable processes and/or tools. For example, in one or moreembodiments, a water jet cutting process can be used to modify theperipheral edge 209-1 of the wafer. That is, a water jet cutter can beused to remove the edge portions 255 of wafer 201 to create theperpendicular blade entry surfaces 209-2 and 209-3. Embodiments are notlimited to a particular type of process and/or tool used to modify theinitial peripheral edge 209-1 of the wafer 201. For instance, a drylaser dicing tool or other suitable tool can be used to remove edgeportions 255 of the wafer 201.

In one or more embodiments, a rotating dicing blade is used to singulatedice 215 by cutting along dicing paths 205 subsequent to modification ofthe wafer edge 209-1 by a first tool, e.g., a water jet or dry laser.However, embodiments of the present disclosure are not limited to aparticular dicing process and/or tool used to singulate the dice 215subsequent to modification of the initial peripheral edge 209-1. Forexample, the dicing of the wafer 201 can occur with dicing tools such asa water jet or dry laser cutter, among other dicing tools. Also, inembodiments in which a rotating saw blade is used to singulate the dice215 subsequent to modification of the wafer edge 209-1, embodiments arenot limited to a particular type and/or size of dicing blade 225.

In one or more embodiments, a first tool, e.g., a water jet cutter, isused to change the initial peripheral edge 209-1 of the wafer 201, and asecond tool, e.g., a dicing blade, is used to subsequently dice thewafer along the dicing paths 205. That is, in one or more embodiments,the tool used to perform the wafer modification is different from thetool used to singulate the dice 215 from the wafer.

Processing a wafer according to embodiments of the present disclosurecan have various benefits. For instance, modifying the initialperipheral edge of a wafer to create a number of edge surfacessubstantially perpendicular to the dicing paths can reduce and/orprevent a dicing blade from deflecting and/or wobbling upon makingcontact with the edge of the wafer during dicing. As mentioned above,reducing blade deflection and/or wobble can prevent blade dulling whichcan enhance the useful life of a dicing blade and can increase theaccuracy and/or quality of a dicing cut, among other benefits.

Using a first tool, other than a dicing saw, to modify the initialperipheral edge 209-1 can have various benefits. For example, inembodiments in which a dicing blade is used to singulate the dice 215subsequent to modification of the initial peripheral edge 209-1,removing the edge portions 255 with a tool other than a dicing blade canincrease processing throughput. For instance, in many cases, a water jetcutter or laser cutter can cut at a faster rate than a saw blade. As anexample, a water jet may cut at a rate of about 50 mm/s while a dicingblade may cut at a rate of about 4 mm/s. In such cases, a water jetcutter can relatively rapidly remove the edge portions 255, which thenreduces the amount of material, e.g., the length of the dicing path 205,the dicing blade 225 cuts through during dicing.

In one or more embodiments, the wafer 201 can be a wafer stack, e.g., anumber of wafers bonded together. In such embodiments, the tool and/orprocess used to modify the initial peripheral edge 209-1 and/or the tooland/or process used to dice the wafer stack 201 along the dicing paths205 can be configured to cut through a first wafer of the wafer stack201 and at least partially through a second wafer of the wafer stack201.

FIG. 3A illustrates a top view of the wafer 201 shown in FIG. 2subsequently to being modified in accordance with an embodiment of thepresent disclosure. That is, the wafer 300 shown in FIG. 3A illustratesan embodiment of a peripheral edge 309 of a wafer, e.g., wafer 201 shownin FIG. 2, subsequent to being changed as described in FIG. 2 above.

In the embodiment illustrated in FIG. 3A, arrows 325 are used torepresent a dicing blade making contact with the peripheral edge 309 ofa modified wafer 300 at a blade entry point 307. In one or moreembodiments, and as shown in FIG. 3A, the dicing blade 325 makes contactwith the peripheral edge 309 at an entry angle which is substantiallyperpendicular to a particular portion edge surface 309. As illustratedin FIG. 3A, the peripheral edge 309 of the modified wafer 300 is suchthat each modified edge portion is perpendicular to at least one dicingpath 305.

In the embodiment illustrated in FIG. 3A, the modified wafer 300 is amodified wafer stack 300 that includes a number of unsingulated dice 315to be cut along dicing paths 305. FIG. 3B illustrates a perspective viewof the wafer stack 300 subsequently to being modified in accordance withan embodiment of the present disclosure.

As illustrated in FIG. 3B, the modified wafer stack 300 includes anumber of wafer layers 302, 304, and 306. As described above inconnection with FIGS. 1A-1E, the layers 302, 304, and 306 can becomprised of one or more materials. In one or more embodiments, at leastone of the wafer layers 302, 304, and 306 includes a glass material.Embodiments are not limited to a particular number of layers or to thetype or types of materials of which the layers are formed.

In one or more embodiments, the layers 302, 304, and 306 form a waferlens stack 300, e.g., wafer lens stack 101 described in FIG. 1A-1C. Inone or more embodiments, the dice 315 of wafer stack 300 are singulatedalong dicing paths 305 to form a number of lens assemblies, e.g., lensassemblies 115-1, 115-2, 115-3, and 115-4, shown in FIG. 1E.

FIG. 4A illustrates a wafer processing system 400 according to anembodiment of the present disclosure. In the embodiment illustrated inFIG. 4A, the wafer processing system 400 includes a controller 440. Thecontroller 440 is coupled to a first tool 410-1, e.g., a wafer modifier410-1, a second tool, e.g., a dicer 410-2, and to a wafer holder 470.

The controller 440 includes a memory resource 450 and a processor 460.The memory 450 can include program instructions stored thereon that canbe executed by the processor 460 to control processing of a wafer orwafer stack according to embodiments described herein.

For instance, in one or more embodiments, the wafer modifier 410-1 caninclude a water jet cutter or dry laser cutter, among various wafermodification tools that can be controlled via controller 440 to modifyan initial peripheral edge of a wafer or wafer stack 401, e.g., waferstack 101 shown in FIG. 1B or wafer stack 300 shown in FIG. 3A. Thedicer 410-2 can include a rotating saw blade such as a diamond dicingblade, among various other suitable dicing tools that can be controlledvia controller 440 to dice the wafer or wafer stack 401 subsequent tobeing modified via wafer modifier 410-1. As one of ordinary skill in theart will appreciate, the controller 440 can control the processingtechniques and positioning of the tools 410-1 and 410-2, as well as thepositioning of the wafer 401 and/or wafer holder 470.

FIG. 4B illustrates a wafer processing system 403 according to anembodiment of the present disclosure. In the embodiment illustrated inFIG. 4B, the wafer processing system 403 includes a controller 440.Although not shown in FIG. 4B, the controller 440 can include memoryresources and a processor as described in connection with FIG. 4A.

In the embodiment illustrated in FIG. 4B, the controller 440 is coupledto a water jet cutter 411 that can be used to change an initialperipheral edge of a wafer of wafer stack 401 as described herein above.In this embodiment, the controller 440 is also coupled to a dicing saw413 that can be used to dice the modified wafer along a number of dicingpaths.

According to one or more embodiments, the modification via water jet 411creates a number of edge surfaces substantially perpendicular to anumber of dicing paths associated with wafer 401. The dicing saw 413 isused to dice the modified wafer along the number of dicing paths, and asdescribed above, the blade of the dicing saw 413 contacts the modifiededge surfaces of the wafer at a perpendicular entry angle.

FIG. 5 illustrates a lens stack device 580 in accordance with anembodiment of the present disclosure. The lens stack device 580 includesa lens stack 515, e.g., lens stack assemblies 115-1, 115-2, 115-3, and115-4 described in connection with FIG. 1E. The lens stack 515 can be adie that is singulated from a wafer according to one or more waferprocessing embodiments described herein.

In the embodiment illustrated in FIG. 5, the lens stack 515 is coupledto, e.g., bonded, to an image sensor 575. Although not shown in FIG. 5,the image sensor 575 can include a number of layers having image sensingcircuitry, a color filter array, and/or electrical connections, amongother components known to one or ordinary skill in the art. The lensstack device 580 can be used in a variety of electronic devices andsystems, such as a computer system, still or video camera system,scanner, machine vision, vehicle navigation, video phone, surveillancesystem, auto focus system, star tracker system, motion detection system,image stabilization system, and data compression system, among others.

FIG. 6 illustrates a block diagram of an electronic system 690 having atleast one lens stack device 680, e.g., lens device 580 shown in FIG. 5,formed in accordance with an embodiment of the present disclosure. Inthe embodiment illustrated in FIG. 6, the system 690 includes a display692, a lens stack device 680, and subsystems 694 that are coupledtogether via bus 682. The subsystems 682 may include, for example,hardware, firmware and/or software for storage, control, and interfaceoperations of the electronic system 690 that are known to one ofordinary skill in the art; accordingly, a detailed description is notprovided.

The electronic system 690 can be a computer system, still or videocamera system, scanner, machine vision, vehicle navigation, video phone,surveillance system, auto focus system, star tracker system, motiondetection system, image stabilization system, and data compressionsystem, and/or telecommunication systems, among others.

Methods, devices, and systems for wafer processing are described herein.One method of wafer processing includes modifying a peripheral edge of awafer to create a number of edge surfaces substantially perpendicular toa number of dicing paths and dicing the wafer along the number of dicingpaths. In one or more embodiments, the method includes modifying theperipheral edge of the wafer with a first tool and dicing the wafer witha second tool different from the first tool.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of one or more embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of skill in the art uponreviewing the above description. The scope of the one or moreembodiments of the present disclosure includes other applications inwhich the above structures and methods are used. Therefore, the scope ofone or more embodiments of the present disclosure should be determinedwith reference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

In the foregoing Detailed Description, one or more features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thus,the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment.

1. A method of wafer processing, comprising: forming a number of lenseson a first wafer; forming a number of lenses on a second wafer; forminga wafer lens stack by bonding the first and second wafer together;creating a number of blade entry edge surfaces that are substantiallyperpendicular to a number of dicing paths by removing a number ofperipheral edge portions of the wafer lens stack; and dicing the waferlens stack along the number of dicing paths.
 2. The method of claim 1,wherein the method includes bonding at least a third wafer to the waferlens stack prior to removing the number of peripheral edge portions ofthe wafer lens stack.
 3. The method of claim 1, wherein the methodincludes dicing the wafer lens stack by using a rotating saw blade andremoving the number of peripheral edge portions with a tool other than arotating saw blade.
 4. The method of claim 1, wherein forming the waferlens stack includes forming a wafer lens stack having a round peripheraledge.
 5. The method of claim 1, wherein dicing the wafer lens stackincludes: applying a saw blade to at least one blade entry pointassociated with each of the number of blade entry edge surfaces, each ofthe at least one blade entry points corresponding to a particular dicingpath; and wherein the saw blade enters each of the number of blade entrysurfaces at the at least one blade entry point such that the saw bladeenters perpendicular to the number of blade entry edge surfaces.
 6. Themethod of claim 1, wherein the number of blade entry edge surfaces areoriented in a first direction and the number of dicing paths areoriented in a second direction; wherein removing the number ofperipheral edge portions of the wafer lens stack includes cutting aperipheral edge of the wafer lens stack along a number of cut linesoriented in the first direction; and wherein at least one of the numberof cut lines oriented in the first direction is unaligned with at leastone of a number of dicing paths oriented in the first direction.
 7. Themethod of claim 6, wherein the method includes cutting the peripheraledge of the wafer lens stack along a number of cut lines oriented in thesecond direction to create a number of blade entry edge surfacesoriented in the second direction and substantially perpendicular to thenumber of dicing paths oriented in the first direction.
 8. The method ofclaim 7, wherein the method includes dicing the wafer lens stack alongthe number of dicing paths oriented in the first direction by cuttingthrough the created number of blade entry surfaces oriented in thesecond direction.
 9. The method of claim 8, wherein including cuttingthrough the created number of blade entry surfaces oriented in thesecond direction at a substantially perpendicular angle.
 10. The methodof claim 1, wherein the method includes: removing the number ofperipheral edge portions of the wafer lens stack using a first tool; anddicing the wafer lens stack using a second tool different from the firsttool.
 11. A wafer processing system, comprising: a first tool used tochange a peripheral edge of a wafer to be subsequently diced along anumber of predetermined dicing paths into a number of devices, whereinthe changing produces at least one edge surface substantiallyperpendicular to at least one of the number of dicing paths for each ofthe dicing paths; and a second tool used to dice the wafer along thenumber of dicing paths.
 12. The system of claim 11, wherein the wafer isa number of stacked wafers bonded together.
 13. The system of claim 12,wherein the first tool and the second tool are configured to cut througha first wafer and at least partially through a second wafer of thenumber of stacked wafers.
 14. The system of claim 12, wherein at leastone of the number of stacked wafers includes a glass material.
 15. Thesystem of claim 13, wherein the second tool is a rotating diamond sawblade.
 16. The system of claim 11, wherein the produced at least oneedge surface associated with each of the dicing paths allows a rotatingdicing blade of the second tool to contact the produced at least oneedge surface perpendicular to the edge surface for each of the number ofdicing paths.
 17. The system of claim 11, wherein the number of devicesinclude a number of lens assemblies.
 18. An electronic system,comprising: a display coupled to a control subsystem; and a lens devicecoupled to the display and control subsystem, the lens device includinga lens assembly coupled to an image sensor; and wherein the lensassembly is diced from a wafer stack subsequent to an initialmodification of a peripheral edge of the wafer stack, and wherein themodification includes creating a number of edge surfaces substantiallyperpendicular to a number of dicing paths.
 19. The system of claim 18,wherein: the wafer stack has a round peripheral edge prior to theinitial modification; and the number of edge surfaces substantiallyperpendicular to the number of dicing paths are created using a firsttool that is different than a second tool used to dice the lens assemblyfrom the wafer stack.
 20. The system of claim 18, wherein the system isat least one of a digital camera system and a cellular telephone system.